JPWO2010035496A1 - Wireless transmission apparatus and wireless transmission method - Google Patents

Abstract

To provide a radio transmission apparatus and a radio transmission method that reduce a collision occurrence rate of transmission packets even when scheduling information reception fails in a retransmission method in which adaptive HARQ and non-adaptive HARQ are combined. In ST301, the resource control section (206) stores the resource allocation information and scheduling timing information transmitted from the base station (100), and in ST302, determines whether or not the scheduling information has been acquired. In ST303, adaptive HARQ is applied. In ST304, it is determined whether the scheduling information that could not be acquired in ST302 could not be acquired at the timing indicated by the scheduling timing information. In ST305, the resource control unit (206) instructs the packet transmission stop. In ST306, the resource control unit (206) applies non-adaptive HARQ.

Description

  The present invention relates to a radio transmission apparatus and a radio transmission method using a retransmission method in which adaptive HARQ (adaptive hybrid auto repeat request) and non-adaptive hybrid auto repeat request (HARQ) are combined.

  One error control technique is HARQ. HARQ is a technique for improving error correction capability and realizing high-quality transmission by retransmitting an erroneous packet on the transmission side and combining the received packet and the retransmission packet on the reception side. This HARQ technology is adopted in HSDPA (High Speed Downlink Packet Access) and LTE (Long Term Evolution).

  As HARQ methods, adaptive HARQ (adaptive HARQ) and non-adaptive HARQ (non-adaptive HARQ) are being studied. Adaptive HARQ is a method of assigning retransmission packets to arbitrary resources. On the other hand, non-adaptive HARQ is a method of assigning retransmission packets to predetermined resources.

  Adaptive HARQ allocates a packet to a resource with good channel quality at the time of transmission, so that the packet error rate can be improved and the number of retransmissions can be reduced. Conversely, since a packet is assigned to an arbitrary resource, signaling for notifying the location of the assigned resource of the packet is required every time the packet is transmitted, and there is a problem that signaling overhead increases.

  On the other hand, since non-adaptive HARQ allocates packets to predetermined resources, the channel quality at the time of transmission is not necessarily good, and the average packet error rate tends to increase, so the number of retransmissions tends to increase. It becomes. Conversely, since packets are allocated to predetermined resources, there is no need to notify the packet allocation resource position every time the packet is transmitted, and there is an advantage that signaling overhead is small.

  Thus, there is a trade-off relationship between the number of retransmissions and the signaling overhead between adaptive HARQ and non-adaptive HARQ. Therefore, as a method for solving this trade-off relationship, semi-adaptive HARQ (semi-adaptive HARQ) in which adaptive HARQ and non-adaptive HARQ are combined has been proposed.

  Here, the semi-adaptive HARQ will be described assuming uplink packet transmission. In the semi-adaptive HARQ, the base station performs signaling for notifying the location of the resource, that is, the scheduling information only when it is desired to change the resource allocation. If the mobile station (hereinafter referred to as “UE: User Equipment”) does not receive the signaling from the base station, it determines that the scheduling information addressed to itself is not transmitted from the base station, and uses a predetermined resource. Send the packet. On the other hand, when the signaling from the base station can be received, the UE transmits a packet at the resource position notified by the signaling. That is, the UE switches between adaptive HARQ and non-adaptive HARQ according to the presence / absence of signaling from the base station.

  As described above, the semi-adaptive HARQ allows the base station to transmit signaling as necessary and change the allocation resource position of the packet, so that the number of retransmissions can be reduced with a small signaling overhead.

3GPP TS 36.300 V8.3.0 Technical Specification Group Radio Access Network; E-UTRA and E-UTRAN; Overall description; Stage 2 (Release 8), "11 Scheduling and Rate Control"

  However, in the above-described technique, when a UE fails to receive resource allocation signaling, a packet is transmitted using a predetermined resource. Therefore, when another UE transmits a packet using the same resource, There is a problem that a collision occurs.

  An object of the present invention is to provide a radio transmission apparatus and a radio transmission method that reduce a collision occurrence rate of transmission packets even when reception of scheduling information fails in a retransmission method combining adaptive HARQ and non-adaptive HARQ. It is.

  The wireless transmission device of the present invention, based on the timing to acquire scheduling information and the presence or absence of acquisition of the scheduling information, resource control means for generating resource control information for controlling resources, based on the resource control information, Resource selection means for selecting a resource, and transmission means for transmitting data using the selected resource, wherein the resource control means transmits the data when the scheduling information is not acquired at the timing A configuration for instructing the stop is adopted.

  The radio transmission method of the present invention includes a resource control step for generating resource control information for controlling resources based on the timing for acquiring scheduling information and the presence or absence of acquisition of the scheduling information, and based on the resource control information. A resource selection step of selecting a resource; and a transmission step of transmitting data using the selected resource, wherein the resource control step transmits the data when the scheduling information is not acquired at the timing Instructed to stop.

  According to the present invention, in the retransmission method combining adaptive HARQ and non-adaptive HARQ, it is possible to reduce the collision occurrence rate of transmission packets even when reception of scheduling information fails.

The block diagram which shows the structure of the base station which concerns on Embodiment 1 of this invention. The block diagram which shows the structure of UE which concerns on Embodiment 1 of this invention. FIG. 2 is a flowchart showing an operation procedure of the resource control unit shown in FIG. The figure which uses for description of operation | movement with the base station shown in FIG. 1, and UE shown in FIG. The figure which uses for description of the other operation | movement with the base station shown in FIG. 1, and UE shown in FIG. The block diagram which shows the structure of the base station which concerns on Embodiment 2 of this invention. The block diagram which shows the structure of UE which concerns on Embodiment 2 of this invention. The figure which shows the signaling timing of scheduling information The figure which shows a mode that non-adaptive HARQ is applied

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. However, in the embodiment, components having the same function are denoted by the same reference numerals, and redundant description is omitted.

(Embodiment 1)
The configuration of base station apparatus (hereinafter simply referred to as “base station”) 100 according to Embodiment 1 of the present invention will be described with reference to FIG. FIG. 1 is a block diagram showing a configuration of base station 100 according to Embodiment 1 of the present invention. In FIG. 1, a radio reception unit 102 receives a signal transmitted from a UE from an antenna 101, performs reception processing such as down-conversion and A / D conversion on the received signal, and outputs the received signal to a demodulation unit 103. Also, a reference signal for reception quality measurement included in the reception signal is output to reception quality measurement section 107.

  Demodulation section 103 performs demodulation processing on the signal output from radio reception section 102 and outputs the demodulation result to decoding section 104. Decoding section 104 performs error correction decoding such as turbo decoding and maximum likelihood decoding of convolutional code on the demodulation result output from demodulation section 103 to obtain decoded data, and outputs the decoded data to error detection section 105. . When a detection result indicating no error is acquired from an error detection unit 105 described later, the decoded data is output as received data.

  The error detection unit 105 detects whether or not the decoded data (packet) is incorrect from a CRC (Cyclic Redundancy Check) code added to the decoded data output from the decoding unit 104, and decodes the detection result. Unit 104 and response signal generator 106.

  The response signal generation unit 106 generates NACK when the detection result output from the error detection unit 105 indicates that there is an error, and generates ACK when the detection result indicates that there is no error, and sends ACK or NACK to the modulation unit 111. Output.

  The reception quality measurement unit 107 measures reception quality such as SINR (Signal to Interference and Noise Ratio) of a resource capable of transmitting a packet based on the reference signal for reception quality measurement output from the radio reception unit 102, The measurement result is output to the scheduling unit 109.

  The signaling timing determination unit 108 determines the timing (signaling timing) at which the base station 100 notifies the UE of scheduling information from the packet information such as the UE's moving speed, transport block size (TBS), QoS, The determined signaling timing is output to scheduling section 109 and the signaling timing is output to encoding section 110 as scheduling timing information.

  The scheduling unit 109 has functions of non-adaptive HARQ and adaptive HARQ, and switches between non-adaptive HARQ and adaptive HARQ according to the signaling timing output from the signaling timing determination unit 108. Note that the scheduling unit 109 may determine arbitrary timing and switch between non-adaptive HARQ and adaptive HARQ at the determined timing.

  When non-adaptive HARQ is applied, the scheduling unit 109 does not output resource allocation information because the resource of the retransmission packet transmitted by each UE is determined in advance. However, the resource allocation information is notified to the UE before the retransmission process starts.

  On the other hand, when adaptive HARQ is applied, the scheduling section 109 determines a packet resource to be transmitted by each UE based on the reception quality measurement result output from the reception quality measurement section 107, and uses the determined resource as scheduling information. The data is output to the encoding unit 110. However, in the scheduling information, an identifier (UE ID) for identifying the UE is multiplexed and notified to the UE for each retransmission packet.

  When the scheduling timing information is output from the signaling timing determination unit 108, the encoding unit 110 performs error correction encoding such as a turbo code or a convolutional code on the scheduling timing information. In addition, when the scheduling information is output from the scheduling unit 109, the encoding unit 110 performs error correction encoding such as a turbo code or a convolutional code on the scheduling information. The encoding unit 110 outputs the encoded data obtained by these to the modulation unit 111.

  Modulation section 111 performs modulation processing such as QPSK or 16QAM on the encoded data output from encoding section 110, and outputs the modulated signal to radio transmission section 112. The wireless transmission unit 112 performs transmission processing such as D / A conversion, up-conversion, and amplification on the modulated signal output from the modulation unit 111, and wirelessly transmits the signal subjected to the transmission processing from the antenna 101.

  Next, the configuration of UE 200 according to Embodiment 1 of the present invention will be described using FIG. FIG. 2 is a block diagram showing a configuration of UE 200 according to Embodiment 1 of the present invention. In FIG. 2, the radio reception unit 202 receives the control signal transmitted from the base station 100 from the antenna 201, performs reception processing such as down-conversion and A / D conversion on the received control signal, and outputs the received control signal to the demodulation unit 203. To do.

  Demodulation section 203 performs demodulation processing on the control signal output from radio reception section 202 and outputs the demodulation result to decoding section 204. The decoding unit 204 obtains decoded data by performing error correction decoding such as turbo decoding and maximum likelihood decoding of a convolutional code on the demodulation result output from the demodulation unit 203, and among the obtained decoded data, adaptive HARQ. The scheduling information included at the time of application is output to the identification unit 205. On the other hand, of the acquired decoded data, predetermined resource allocation information and scheduling timing information used when applying non-adaptive HARQ are output to the resource control unit 206.

  The identification unit 205 determines whether the scheduling information output from the decoding unit 204 is information addressed to the own station based on an identifier (UE ID) multiplexed in the scheduling information. If it is determined that the scheduling information is addressed to the own station, the scheduling information is output to the resource control unit 206.

  The resource control unit 206 performs packet allocation according to the predetermined resource allocation information and scheduling timing information for non-adaptive HARQ output from the decoding unit 204 and the scheduling information for adaptive HARQ output from the identification unit 205. The resource allocation position or packet transmission stop is determined, and resource control information indicating the determined content is generated and output to the resource selection unit 209.

  Specifically, when the scheduling information is not output from the identification unit 205 other than the timing at which the scheduling information is acquired, the resource control unit 206 applies non-adaptive HARQ, and sets predetermined resource allocation information to the resource selection unit 209. Output to. When scheduling information is output from the identification unit 205, the resource control unit 206 applies adaptive HARQ, and outputs the resource indicated by the scheduling information to the resource selection unit 209. Further, when scheduling information is not output from the identification unit 205 at the timing of acquiring scheduling information, resource control information for instructing to stop packet transmission is output to the resource selection unit 209.

  Encoding section 207 performs error correction encoding such as turbo code or convolutional code on the transmission data, and outputs the encoded data to modulation section 208. Modulation section 208 performs modulation processing such as QPSK or 16QAM on the encoded data output from encoding section 207, and outputs the modulated signal to resource selection section 209.

  Based on the resource control information output from the resource control unit 206, the resource selection unit 209 selects a resource to which the modulation signal output from the modulation unit 208 is allocated, allocates the modulation signal to the selected resource, and transmits the radio transmission unit 210. Output to.

  The wireless transmission unit 210 performs transmission processing such as D / A conversion, up-conversion, and amplification on the modulated signal output from the resource selection unit 209, and wirelessly transmits the signal subjected to the transmission processing from the antenna 201.

  Next, the operation of the resource control unit 206 described above will be described with reference to FIG. FIG. 3 is a flowchart showing an operation procedure of the resource control unit 206 shown in FIG. In step (hereinafter abbreviated as “ST”) 301 in FIG. 3, the resource control unit 206 acquires and stores resource allocation information and scheduling timing information transmitted from the base station 100.

  In ST302, the resource control unit 206 determines whether or not the scheduling information has been acquired from the identification unit 205, and when the scheduling information is acquired (YES), the process proceeds to ST303 and the scheduling information is not acquired ( NO), the process proceeds to ST304.

  In ST303, the resource control unit 206 applies adaptive HARQ, notifies the resource selection unit 209 of the resource indicated by the scheduling information acquired in ST302, and ends the operation of the resource control unit 206.

  In ST304, it is determined whether the scheduling information that could not be acquired in ST302 could not be acquired at the timing (scheduling timing) indicated by the scheduling timing information stored in ST301. If it cannot be acquired at the scheduling timing (YES), the process proceeds to ST305, and if it cannot be acquired at a timing other than the timing indicated by the scheduling information (NO), the process proceeds to ST306.

  In ST305, the resource control unit 206 notifies the resource selection unit 209 of a packet transmission stop instruction, and ends the operation of the resource control unit 206.

  In ST306, the resource control unit 206 applies non-adaptive HARQ, notifies the resource selection unit 209 of the resource stored in ST301, and ends the operation of the resource control unit 206.

  Next, operations of base station 100 shown in FIG. 1 and UE 200 shown in FIG. 2 will be described using FIG. First, FIG. 4A shows the collision rate of packets in semi-adaptive HARQ. Here, the horizontal axis represents time (t), and the vertical axis represents the collision occurrence rate. As shown in FIG. 4A, the packet collision occurrence rate is not uniform in time and varies depending on the number of retransmissions. The timing when the collision occurrence rate becomes high is after a certain time has elapsed since the resource was allocated by signaling. That is, the number of retransmissions N (N = 2 in FIG. 4A) after which resource allocation is required again. This is because resource allocation by signaling is generally performed so as to be optimal at that time based on the channel quality assumed at the time of packet transmission and the allocation status of a plurality of UEs.

  Here, if a packet error occurs and the packet is retransmitted, the time has elapsed since the time when the resource was allocated, and the channel quality at the time of resource allocation and the current channel due to the time variation of the channel There is a gap with quality. For this reason, it is necessary to reallocate resources after a certain period of time. When reallocating resources, signaling for resource notification is concentrated in a plurality of UEs. Therefore, at this timing, the number of UEs that should receive signaling increases, and accordingly, the number of UEs that fail to receive signaling also increases, and the packet collision occurrence rate increases.

  FIG. 4B shows frequency and time resources used by a plurality of UEs for packet transmission. Here, two UEs, UE # A and UE # B, are illustrated. In addition, RB (Resource Block) # 1 and RB # 2 are used as frequency resources, and initial transmission timing, first retransmission, and second retransmission timing are used as time resources. Note that retransmission is performed at an RTT (Round Trip Time) interval.

  The base station allocates RB # 1 to UE # A in advance as a resource for retransmission, and notifies resource allocation information to UE # A in advance. Similarly, RB # 2 is allocated to UE # B in advance as a resource for retransmission, and resource allocation information is notified to UE # B in advance. Further, the base station notifies the scheduling information (grant) at the second retransmission timing, and notifies the UE # A and UE # B of this timing in advance.

  Since UE #A and UE #B are not notified of scheduling information from the base station at the first retransmission timing, they transmit packets according to the resource allocation information notified in advance. When scheduling information is notified from the base station, a packet is transmitted according to the scheduling information.

  Subsequently, at the second retransmission timing, the base station signals scheduling information. Here, it is assumed that the base station reassigns RB # 2 to UE # A and RB # 1 to UE # B. Since UE #A and UE #B know in advance that the scheduling information is notified, the UE #A and the UE #B transmit packets according to the scheduling information notified from the base station. Here, assuming that UE # B has correctly received scheduling information, RB # 1 transmits a packet. On the other hand, assuming that UE # A fails to receive scheduling information, it stops transmitting packets.

  As described above, according to the first embodiment, the signaling timing of the scheduling information is notified in advance from the base station to the UE, and the UE stops transmitting the packet when the scheduling information reception fails at the notified signaling timing. By doing so, it is possible to avoid a collision with a transmission packet of another UE.

  Note that as the number of retransmissions increases, the number of retransmission packets decreases, so the signaling of scheduling information transmitted to each UE also decreases. Therefore, when the scheduling information can be identified at a timing earlier than the timing notified in advance (not including the timing notified), the resource control unit 206 of the UE 200 controls to transmit the packet according to the scheduling information. Further, when the scheduling information cannot be identified, the resource control unit 206 performs control so that the packet is transmitted according to the resource notified in advance. Further, the resource control unit 206 controls to stop packet transmission when scheduling information cannot be identified after the previously notified timing (including the notified timing).

  Here, it demonstrates concretely using FIG. FIG. 5A shows that the number of retransmission packets decreases as the number of retransmissions increases. FIG. 5B shows the frequency and time resources used by the UE for packet transmission and the presence / absence of scheduling information (grant).

  The base station 100 allocates retransmission resources to the UE 100 and notifies the UE 200 of resource allocation information in advance. Furthermore, the base station 100 notifies the scheduling information at a timing after the retransmission M-th time, and notifies the UE 200 in advance of this timing.

  When the scheduling information is notified from the base station 100 at a timing earlier than the M-th retransmission, the UE 200 transmits a packet according to the scheduling information. In the case of FIG. 5, scheduling information is notified at the first retransmission, and scheduling information is not notified at the retransmission M−1.

  On the other hand, the base station 100 signals scheduling information at the timing after the M-th retransmission. Since the UE 200 knows in advance that the scheduling information is notified, the UE 200 transmits a packet according to the scheduling information notified from the base station 100. In addition, when reception of the scheduling information notified from the base station 100 fails, the UE 200 stops packet transmission.

  In this way, by setting the scheduling information signaling in a period in which the number of retransmission packets decreases, it is possible to suppress an increase in signaling overhead and reduce the number of collisions of transmission packets of the UE.

(Embodiment 2)
The configuration of base station 400 according to Embodiment 2 of the present invention will be described using FIG. FIG. 6 is a block diagram showing a configuration of base station 400 according to Embodiment 2 of the present invention. FIG. 6 differs from FIG. 1 in that the signaling timing determination unit 108 is changed to a signaling timing determination unit 401.

  The signaling timing determination unit 401 associates the signaling timing of the scheduling information with parameters such as transport block size (TBS), QoS delay, presence / absence of frequency hopping of transmission packets, path loss between transmission and reception, etc. Based on the parameters, signaling timing is determined. The determined signaling timing is output to scheduling section 109.

  Note that signaling timing determination section 401 does not output signaling timing (scheduling timing information) to encoding section 110, unlike signaling timing determination section 108 of base station 100 according to Embodiment 1. That is, base station 400 according to the present embodiment does not explicitly notify the scheduling timing information to the UE.

  The configuration of UE 500 according to Embodiment 2 of the present invention will be described using FIG. FIG. 7 is a block diagram showing a configuration of UE 500 according to Embodiment 2 of the present invention. FIG. 7 differs from FIG. 2 in that a signaling timing determination unit 501 is added.

  The signaling timing determination unit 501 has the same function as the signaling timing determination unit 401 of the base station 400, and sets the signaling timing of scheduling information such as TBS of transmission packets, QoS delay, presence / absence of frequency hopping, path loss between transmission and reception, etc. And signaling timing is determined based on these parameters. The determined signaling timing is output to the resource control unit 206.

  The signaling timing determination units 401 and 501 may be any one of the signaling timing of the scheduling information, the TBS of the transmission packet, the QoS delay, the presence / absence of frequency hopping, and the path loss between transmission and reception (only one or only one) Need not be associated).

  Next, various parameters associated with the signaling timing in the above-described signaling timing determination units 401 and 501 will be specifically described. First, the TBS of the transmission packet will be described. A UE that transmits a packet having a large TBS, that is, a large amount of transmission data per packet, sets a short time interval from signaling at the time of initial transmission to signaling of scheduling information at the time of retransmission. On the other hand, for a UE that transmits a packet having a small TBS, that is, a small amount of transmission data per packet, a long time interval is set from the signaling at the initial transmission to the signaling of the scheduling information at the retransmission. Here, the magnitude of the TBS indicates the relative magnitude when both are compared. Similarly, the length of the time interval indicates the relative length when both are compared. The reason for setting in this way is as follows.

  When the TBS is large, the amount of resources used per packet transmission increases, so the number of packets that can be transmitted per transmission time unit (for example, sub-frame) decreases. As a result, the number of scheduling information signaling in the system is reduced. Therefore, the signaling interval of scheduling information can be set short. Also, a packet with a large TBS has a large effect on the system throughput, so the adaptability to propagation path fluctuation is increased. That is, the scheduling information signaling interval is set short, and appropriate resource allocation is performed by following the propagation path fluctuation. Thereby, system throughput can be improved.

  On the other hand, when the TBS is small, the amount of resources used per packet transmission is small, so the number of packets that can be transmitted per transmission time unit is large. As a result, the number of scheduling information signaling in the system increases, and it is necessary to set a longer signaling interval.

  Therefore, when the TBS is large, the scheduling information signaling interval is set short, and when the TBS is small, the scheduling information signaling interval is set long. Thus, by associating the signaling timing of the scheduling information with the TBS in advance, it is possible to reduce the collision occurrence rate between packets without generating an overhead for notifying the signaling timing of the scheduling information.

  Next, the QoS delay of the transmission packet will be described. For a UE that transmits a packet with a small QoS delay, that is, a short time until the packet is discarded due to a transmission delay, a time interval from signaling at the time of initial transmission to signaling of scheduling information at the time of retransmission is set short. On the other hand, for a UE that transmits a packet having a large QoS delay, that is, a long time until the packet is discarded due to a transmission delay, a long time interval is set from the signaling at the initial transmission to the signaling of the scheduling information at the retransmission. To do. Here, the magnitude of the QoS delay indicates a relative magnitude when both are compared. Similarly, the length of the time interval indicates the relative length when both are compared. The reason for setting in this way is as follows.

  When the QoS delay is small, the adaptability to propagation path fluctuation is increased. That is, the scheduling information signaling interval is set short, and appropriate resource allocation is performed by following the propagation path fluctuation. As a result, the number of retransmissions is reduced, and the probability that the packet is discarded beyond the request delay is lowered, so that the system throughput can be improved.

  On the other hand, when the QoS delay is large, it takes a long time until the packet is discarded, so that it is highly possible to withstand an increase in the number of retransmissions. That is, the scheduling information signaling interval can be set longer. Therefore, when combined with the case where the QoS delay is small, the signaling overhead of scheduling information can be distributed.

  Therefore, when the QoS delay is large, the scheduling information signaling interval is set to be long, and when the QoS delay is small, the scheduling information signaling interval is set to be short. As described above, by associating the scheduling information signaling timing with the QoS delay in advance, it is possible to reduce the collision occurrence rate between packets without generating an overhead for notifying the scheduling information signaling timing.

  Next, the presence / absence of frequency hopping will be described. For a UE to which frequency hopping is not applied, a time interval from signaling at the time of initial transmission to scheduling information at the time of retransmission is set short. On the other hand, for a UE to which frequency hopping is applied, a time interval from signaling at the time of initial transmission to scheduling information at the time of retransmission is set to be long. The reason for setting in this way is as follows.

  A UE to which frequency hopping is applied has a transmission parameter determined based on the average SINR, and therefore reduces the fitness for instantaneous channel fluctuation. That is, the scheduling information signaling interval can be set longer. Therefore, when combined with the case where frequency hopping is not applied, the signaling overhead of scheduling information can be distributed.

  On the other hand, since the transmission parameter is determined based on the instantaneous SINR, the UE to which frequency hopping is not applied increases the adaptability to the instantaneous propagation path fluctuation. That is, the scheduling information signaling interval is set short, and appropriate resource allocation is performed by following the propagation path fluctuation. Thereby, system throughput can be improved.

  Therefore, when frequency hopping is applied, the scheduling information signaling interval is set long, and when frequency hopping is not applied, the scheduling information signaling interval is set short. In this way, by associating the scheduling information signaling timing with the presence / absence of frequency hopping in advance, it is possible to reduce the collision occurrence rate between packets without generating overhead for notifying the scheduling information signaling timing. it can.

  Next, path loss between transmission and reception will be described. For a UE that has a small path loss, that is, a small amount of propagation path attenuation and a packet that arrives with high reception quality, the time interval from the initial transmission signaling to the retransmission scheduling information signaling is set short. On the other hand, for a UE that has a large path loss, that is, a packet that arrives with low reception quality with a large propagation path attenuation, a long time interval is set from the signaling at the initial transmission to the signaling of the scheduling information at the retransmission. Here, the magnitude of the path loss indicates the relative magnitude when both are compared. Similarly, the length of the time interval indicates the relative length when both are compared. The reason for setting in this way is as follows.

  A UE with a small path loss consumes less resources for signaling scheduling information, and therefore the number of UEs that can transmit signaling for scheduling information in the system increases. Therefore, it is possible to increase the adaptability to propagation path fluctuation, that is, to increase the number of UEs that can set the scheduling information signaling interval to be short, and to improve the system throughput.

  On the other hand, since a UE with a large path loss requires robust transmission, resource consumption for signaling scheduling information increases. As a result, the number of signaling capable UEs of scheduling information per transmission time in the system is reduced, and it is necessary to set a longer signaling interval.

  Therefore, when the path loss is large, the scheduling information signaling interval is set to be long, and when the path loss is small, the scheduling information signaling interval is set to be short. In this manner, by associating the signaling timing of scheduling information with the path loss between transmission and reception in advance, it is possible to reduce the collision occurrence rate between packets without generating overhead for notifying the signaling timing of scheduling information. it can.

  As described above, according to Embodiment 2, the signaling timing of scheduling information is associated with parameters such as TBS of transmission packets, QoS delay, presence / absence of frequency hopping, path loss between transmission and reception, and scheduling is performed based on any parameter. By determining the signaling timing of information, it is possible to reduce the collision occurrence rate between packets without generating overhead for notifying the signaling timing of scheduling information.

(Embodiment 3)
In the first and second embodiments, description has been made assuming uplink packet transmission, but in the third embodiment of the present invention, description will be given assuming downlink packet transmission.

  The base station allocates downlink retransmission resources to each UE in advance, and notifies the UE of resource allocation information in advance. Also, the base station notifies the UE in advance of the timing for notifying scheduling information.

  If the UE receives signaling including scheduling information at a timing other than the timing notified in advance, the UE receives a packet according to the scheduling information. On the other hand, when the scheduling information cannot be received, the packet is received according to the resource allocation information notified in advance. In addition, when the scheduling information cannot be received at the timing notified in advance, the UE stops HARQ combining of the packets.

  As described above, according to the third embodiment, the signaling timing of the scheduling information is notified from the base station to the UE in advance, and when the UE fails to receive the scheduling information at the notified signaling timing, the HARQ combining of the packet is performed. By stopping, it is possible to avoid combining with received packets of other UEs.

  Note that the signaling timing of the scheduling information described in the above embodiments may be a continuous retransmission timing as shown in FIG. Thereby, the reception error of the scheduling information in the signaling timing of scheduling information can be reduced.

  In addition, the signaling timing of the scheduling information may be plural times up to the maximum number of retransmissions. Moreover, the signaling timing of scheduling information may be set for each cell.

  In addition, the signaling timing of the scheduling information may be represented by a reference timing and a difference between the reference timing. At this time, the reference timing may be notified by a broadcast channel (for example, BCH (Broadcast Channel)), and the difference from the reference timing may be notified for each UE. Thereby, the bit number of the signaling transmitted for every UE can be reduced.

  Further, an offset different for each UE may be added to the signaling timing so that the signaling timing of the scheduling information is different for each UE in the same cell. Thereby, the generation of the signaling timing of the scheduling information can be dispersed in time. Therefore, it is possible to reduce the probability that scheduling information is transmitted beyond the number that can be accommodated in downlink control channels (for example, PDCCH (Physical Dedicated Control Channel)). That is, since scheduling information is not transmitted and the probability of occurrence of unscheduled UEs can be reduced, a decrease in throughput can be suppressed.

  Also, when there is little occurrence of packet fragmentation, as shown in FIG. 9, scheduling information is not transmitted at all other than the signaling timing of scheduling information, that is, non-adaptive HARQ may be applied. Thereby, the collision of the packet between UEs at the time of retransmission can be avoided.

  In addition, regarding the application of non-adaptive HARQ, if the UE cannot acquire the scheduling information at the signaling timing of the scheduling information, the retransmission packet is transmitted via the pre-defined resource at the next non-adaptive HARQ retransmission timing. A transmission method is conceivable. Alternatively, if the UE cannot acquire scheduling information, a method of stopping packet transmission until the next scheduling information is signaled can be considered.

  In addition, a base station may be expressed as NodeB or eNodeB.

  Further, although cases have been described with the above embodiment as examples where the present invention is configured by hardware, the present invention can also be realized by software.

  Each functional block used in the description of each of the above embodiments is typically realized as an LSI which is an integrated circuit. These may be individually made into one chip, or may be made into one chip so as to include a part or all of them. The name used here is LSI, but it may also be called IC, system LSI, super LSI, or ultra LSI depending on the degree of integration.

  Further, the method of circuit integration is not limited to LSI's, and implementation using dedicated circuitry or general purpose processors is also possible. An FPGA (Field Programmable Gate Array) that can be programmed after manufacturing the LSI, or a reconfigurable processor that can reconfigure the connection and setting of circuit cells inside the LSI may be used.

  Further, if integrated circuit technology comes out to replace LSI's as a result of the advancement of semiconductor technology or a derivative other technology, it is naturally also possible to carry out function block integration using this technology. Biotechnology can be applied.

  The disclosure of the specification, drawings and abstract contained in the Japanese application of Japanese Patent Application No. 2008-250616 filed on Sep. 29, 2008 is incorporated herein by reference.

The radio transmission apparatus and radio transmission method according to the present invention can be applied to, for example, a mobile communication system.

  The present invention relates to a radio transmission apparatus and a radio transmission method using a retransmission method in which adaptive HARQ (adaptive hybrid auto repeat request) and non-adaptive hybrid auto repeat request (HARQ) are combined.

  One error control technique is HARQ. HARQ is a technique for improving error correction capability and realizing high-quality transmission by retransmitting an erroneous packet on the transmission side and combining the received packet and the retransmission packet on the reception side. This HARQ technology is adopted in HSDPA (High Speed Downlink Packet Access) and LTE (Long Term Evolution).

  As HARQ methods, adaptive HARQ (adaptive HARQ) and non-adaptive HARQ (non-adaptive HARQ) are being studied. Adaptive HARQ is a method of assigning retransmission packets to arbitrary resources. On the other hand, non-adaptive HARQ is a method of assigning retransmission packets to predetermined resources.

  Adaptive HARQ allocates a packet to a resource with good channel quality at the time of transmission, so that the packet error rate can be improved and the number of retransmissions can be reduced. Conversely, since a packet is assigned to an arbitrary resource, signaling for notifying the location of the assigned resource of the packet is required every time the packet is transmitted, and there is a problem that signaling overhead increases.

  On the other hand, since non-adaptive HARQ allocates packets to predetermined resources, the channel quality at the time of transmission is not necessarily good, and the average packet error rate tends to increase, so the number of retransmissions tends to increase. It becomes. Conversely, since packets are allocated to predetermined resources, there is no need to notify the packet allocation resource position every time the packet is transmitted, and there is an advantage that signaling overhead is small.

  Thus, there is a trade-off relationship between the number of retransmissions and the signaling overhead between adaptive HARQ and non-adaptive HARQ. Therefore, as a method for solving this trade-off relationship, semi-adaptive HARQ (semi-adaptive HARQ) in which adaptive HARQ and non-adaptive HARQ are combined has been proposed.

  Here, the semi-adaptive HARQ will be described assuming uplink packet transmission. In the semi-adaptive HARQ, the base station performs signaling for notifying the location of the resource, that is, the scheduling information only when it is desired to change the resource allocation. If the mobile station (hereinafter referred to as “UE: User Equipment”) does not receive the signaling from the base station, it determines that the scheduling information addressed to itself is not transmitted from the base station, and uses a predetermined resource. Send the packet. On the other hand, when the signaling from the base station can be received, the UE transmits a packet at the resource position notified by the signaling. That is, the UE switches between adaptive HARQ and non-adaptive HARQ according to the presence / absence of signaling from the base station.

  As described above, the semi-adaptive HARQ allows the base station to transmit signaling as necessary and change the allocation resource position of the packet, so that the number of retransmissions can be reduced with a small signaling overhead.

3GPP TS 36.300 V8.3.0 Technical Specification Group Radio Access Network; E-UTRA and E-UTRAN; Overall description; Stage 2 (Release 8), "11 Scheduling and Rate Control"

  However, in the above-described technique, when a UE fails to receive resource allocation signaling, a packet is transmitted using a predetermined resource. Therefore, when another UE transmits a packet using the same resource, There is a problem that a collision occurs.

  An object of the present invention is to provide a radio transmission apparatus and a radio transmission method that reduce a collision occurrence rate of transmission packets even when reception of scheduling information fails in a retransmission method combining adaptive HARQ and non-adaptive HARQ. It is.

  The wireless transmission device of the present invention, based on the timing to acquire scheduling information and the presence or absence of acquisition of the scheduling information, resource control means for generating resource control information for controlling resources, based on the resource control information, Resource selection means for selecting a resource, and transmission means for transmitting data using the selected resource, wherein the resource control means transmits the data when the scheduling information is not acquired at the timing A configuration for instructing the stop is adopted.

  The radio transmission method of the present invention includes a resource control step for generating resource control information for controlling resources based on the timing for acquiring scheduling information and the presence or absence of acquisition of the scheduling information, and based on the resource control information. A resource selection step of selecting a resource; and a transmission step of transmitting data using the selected resource, wherein the resource control step transmits the data when the scheduling information is not acquired at the timing Instructed to stop.

  According to the present invention, in the retransmission method combining adaptive HARQ and non-adaptive HARQ, it is possible to reduce the collision occurrence rate of transmission packets even when reception of scheduling information fails.

The block diagram which shows the structure of the base station which concerns on Embodiment 1 of this invention. The block diagram which shows the structure of UE which concerns on Embodiment 1 of this invention. FIG. 2 is a flowchart showing an operation procedure of the resource control unit shown in FIG. The figure which uses for description of operation | movement with the base station shown in FIG. 1, and UE shown in FIG. The figure which uses for description of the other operation | movement with the base station shown in FIG. 1, and UE shown in FIG. The block diagram which shows the structure of the base station which concerns on Embodiment 2 of this invention. The block diagram which shows the structure of UE which concerns on Embodiment 2 of this invention. The figure which shows the signaling timing of scheduling information The figure which shows a mode that non-adaptive HARQ is applied

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. However, in the embodiment, components having the same function are denoted by the same reference numerals, and redundant description is omitted.

(Embodiment 1)
The configuration of base station apparatus (hereinafter simply referred to as “base station”) 100 according to Embodiment 1 of the present invention will be described with reference to FIG. FIG. 1 is a block diagram showing a configuration of base station 100 according to Embodiment 1 of the present invention. In FIG. 1, a radio reception unit 102 receives a signal transmitted from a UE from an antenna 101, performs reception processing such as down-conversion and A / D conversion on the received signal, and outputs the received signal to a demodulation unit 103. Also, a reference signal for reception quality measurement included in the reception signal is output to reception quality measurement section 107.

  Demodulation section 103 performs demodulation processing on the signal output from radio reception section 102 and outputs the demodulation result to decoding section 104. Decoding section 104 performs error correction decoding such as turbo decoding and maximum likelihood decoding of convolutional code on the demodulation result output from demodulation section 103 to obtain decoded data, and outputs the decoded data to error detection section 105. . When a detection result indicating no error is acquired from an error detection unit 105 described later, the decoded data is output as received data.

  The error detection unit 105 detects whether or not the decoded data (packet) is incorrect from a CRC (Cyclic Redundancy Check) code added to the decoded data output from the decoding unit 104, and decodes the detection result. Unit 104 and response signal generator 106.

  The response signal generation unit 106 generates NACK when the detection result output from the error detection unit 105 indicates that there is an error, and generates ACK when the detection result indicates that there is no error, and sends ACK or NACK to the modulation unit 111. Output.

  The reception quality measurement unit 107 measures reception quality such as SINR (Signal to Interference and Noise Ratio) of a resource capable of transmitting a packet based on the reference signal for reception quality measurement output from the radio reception unit 102, The measurement result is output to the scheduling unit 109.

  The signaling timing determination unit 108 determines the timing (signaling timing) at which the base station 100 notifies the UE of scheduling information from the packet information such as the UE's moving speed, transport block size (TBS), QoS, The determined signaling timing is output to scheduling section 109 and the signaling timing is output to encoding section 110 as scheduling timing information.

  The scheduling unit 109 has functions of non-adaptive HARQ and adaptive HARQ, and switches between non-adaptive HARQ and adaptive HARQ according to the signaling timing output from the signaling timing determination unit 108. Note that the scheduling unit 109 may determine arbitrary timing and switch between non-adaptive HARQ and adaptive HARQ at the determined timing.

  When non-adaptive HARQ is applied, the scheduling unit 109 does not output resource allocation information because the resource of the retransmission packet transmitted by each UE is determined in advance. However, the resource allocation information is notified to the UE before the retransmission process starts.

On the other hand, when adaptive HARQ is applied, the scheduling section 109 determines a packet resource to be transmitted by each UE based on the reception quality measurement result output from the reception quality measurement section 107, and uses the determined resource as scheduling information. The data is output to the encoding unit 110. However, in the scheduling information, an identifier (UE ID) for identifying the UE is multiplexed and notified to the UE for each retransmission packet.

  When the scheduling timing information is output from the signaling timing determination unit 108, the encoding unit 110 performs error correction encoding such as a turbo code or a convolutional code on the scheduling timing information. In addition, when the scheduling information is output from the scheduling unit 109, the encoding unit 110 performs error correction encoding such as a turbo code or a convolutional code on the scheduling information. The encoding unit 110 outputs the encoded data obtained by these to the modulation unit 111.

  Modulation section 111 performs modulation processing such as QPSK or 16QAM on the encoded data output from encoding section 110, and outputs the modulated signal to radio transmission section 112. The wireless transmission unit 112 performs transmission processing such as D / A conversion, up-conversion, and amplification on the modulated signal output from the modulation unit 111, and wirelessly transmits the signal subjected to the transmission processing from the antenna 101.

  Next, the configuration of UE 200 according to Embodiment 1 of the present invention will be described using FIG. FIG. 2 is a block diagram showing a configuration of UE 200 according to Embodiment 1 of the present invention. In FIG. 2, the radio reception unit 202 receives the control signal transmitted from the base station 100 from the antenna 201, performs reception processing such as down-conversion and A / D conversion on the received control signal, and outputs the received control signal to the demodulation unit 203. To do.

  Demodulation section 203 performs demodulation processing on the control signal output from radio reception section 202 and outputs the demodulation result to decoding section 204. The decoding unit 204 obtains decoded data by performing error correction decoding such as turbo decoding and maximum likelihood decoding of a convolutional code on the demodulation result output from the demodulation unit 203, and among the obtained decoded data, adaptive HARQ. The scheduling information included at the time of application is output to the identification unit 205. On the other hand, of the acquired decoded data, predetermined resource allocation information and scheduling timing information used when applying non-adaptive HARQ are output to the resource control unit 206.

  The identification unit 205 determines whether the scheduling information output from the decoding unit 204 is information addressed to the own station based on an identifier (UE ID) multiplexed in the scheduling information. If it is determined that the scheduling information is addressed to the own station, the scheduling information is output to the resource control unit 206.

  The resource control unit 206 performs packet allocation according to the predetermined resource allocation information and scheduling timing information for non-adaptive HARQ output from the decoding unit 204 and the scheduling information for adaptive HARQ output from the identification unit 205. The resource allocation position or packet transmission stop is determined, and resource control information indicating the determined content is generated and output to the resource selection unit 209.

  Specifically, when the scheduling information is not output from the identification unit 205 other than the timing at which the scheduling information is acquired, the resource control unit 206 applies non-adaptive HARQ, and sets predetermined resource allocation information to the resource selection unit 209. Output to. When scheduling information is output from the identification unit 205, the resource control unit 206 applies adaptive HARQ, and outputs the resource indicated by the scheduling information to the resource selection unit 209. Further, when scheduling information is not output from the identification unit 205 at the timing of acquiring scheduling information, resource control information for instructing to stop packet transmission is output to the resource selection unit 209.

Encoding section 207 performs error correction encoding such as turbo code or convolutional code on the transmission data, and outputs the encoded data to modulation section 208. Modulation section 208 performs modulation processing such as QPSK or 16QAM on the encoded data output from encoding section 207, and outputs the modulated signal to resource selection section 209.

  Based on the resource control information output from the resource control unit 206, the resource selection unit 209 selects a resource to which the modulation signal output from the modulation unit 208 is allocated, allocates the modulation signal to the selected resource, and transmits the radio transmission unit 210. Output to.

  The wireless transmission unit 210 performs transmission processing such as D / A conversion, up-conversion, and amplification on the modulated signal output from the resource selection unit 209, and wirelessly transmits the signal subjected to the transmission processing from the antenna 201.

  Next, the operation of the resource control unit 206 described above will be described with reference to FIG. FIG. 3 is a flowchart showing an operation procedure of the resource control unit 206 shown in FIG. In step (hereinafter abbreviated as “ST”) 301 in FIG. 3, the resource control unit 206 acquires and stores resource allocation information and scheduling timing information transmitted from the base station 100.

  In ST302, the resource control unit 206 determines whether or not the scheduling information has been acquired from the identification unit 205, and when the scheduling information is acquired (YES), the process proceeds to ST303 and the scheduling information is not acquired ( NO), the process proceeds to ST304.

  In ST303, the resource control unit 206 applies adaptive HARQ, notifies the resource selection unit 209 of the resource indicated by the scheduling information acquired in ST302, and ends the operation of the resource control unit 206.

  In ST304, it is determined whether the scheduling information that could not be acquired in ST302 could not be acquired at the timing (scheduling timing) indicated by the scheduling timing information stored in ST301. If it cannot be acquired at the scheduling timing (YES), the process proceeds to ST305, and if it cannot be acquired at a timing other than the timing indicated by the scheduling information (NO), the process proceeds to ST306.

  In ST305, the resource control unit 206 notifies the resource selection unit 209 of a packet transmission stop instruction, and ends the operation of the resource control unit 206.

  In ST306, the resource control unit 206 applies non-adaptive HARQ, notifies the resource selection unit 209 of the resource stored in ST301, and ends the operation of the resource control unit 206.

  Next, operations of base station 100 shown in FIG. 1 and UE 200 shown in FIG. 2 will be described using FIG. First, FIG. 4A shows the collision rate of packets in semi-adaptive HARQ. Here, the horizontal axis represents time (t), and the vertical axis represents the collision occurrence rate. As shown in FIG. 4A, the packet collision occurrence rate is not uniform in time and varies depending on the number of retransmissions. The timing when the collision occurrence rate becomes high is after a certain time has elapsed since the resource was allocated by signaling. That is, the number of retransmissions N (N = 2 in FIG. 4A) after which resource allocation is required again. This is because resource allocation by signaling is generally performed so as to be optimal at that time based on the channel quality assumed at the time of packet transmission and the allocation status of a plurality of UEs.

  Here, if a packet error occurs and the packet is retransmitted, the time has elapsed since the time when the resource was allocated, and the channel quality at the time of resource allocation and the current channel due to the time variation of the channel There is a gap with quality. For this reason, it is necessary to reallocate resources after a certain period of time. When reallocating resources, signaling for resource notification is concentrated in a plurality of UEs. Therefore, at this timing, the number of UEs that should receive signaling increases, and accordingly, the number of UEs that fail to receive signaling also increases, and the packet collision occurrence rate increases.

  FIG. 4B shows frequency and time resources used by a plurality of UEs for packet transmission. Here, two UEs, UE # A and UE # B, are illustrated. In addition, RB (Resource Block) # 1 and RB # 2 are used as frequency resources, and initial transmission timing, first retransmission, and second retransmission timing are used as time resources. Note that retransmission is performed at an RTT (Round Trip Time) interval.

  The base station allocates RB # 1 to UE # A in advance as a resource for retransmission, and notifies resource allocation information to UE # A in advance. Similarly, RB # 2 is allocated to UE # B in advance as a resource for retransmission, and resource allocation information is notified to UE # B in advance. Further, the base station notifies the scheduling information (grant) at the second retransmission timing, and notifies the UE # A and UE # B of this timing in advance.

  Since UE #A and UE #B are not notified of scheduling information from the base station at the first retransmission timing, they transmit packets according to the resource allocation information notified in advance. When scheduling information is notified from the base station, a packet is transmitted according to the scheduling information.

  Subsequently, at the second retransmission timing, the base station signals scheduling information. Here, it is assumed that the base station reassigns RB # 2 to UE # A and RB # 1 to UE # B. Since UE #A and UE #B know in advance that the scheduling information is notified, the UE #A and the UE #B transmit packets according to the scheduling information notified from the base station. Here, assuming that UE # B has correctly received scheduling information, RB # 1 transmits a packet. On the other hand, assuming that UE # A fails to receive scheduling information, it stops transmitting packets.

  As described above, according to the first embodiment, the signaling timing of the scheduling information is notified in advance from the base station to the UE, and the UE stops transmitting the packet when the scheduling information reception fails at the notified signaling timing. By doing so, it is possible to avoid a collision with a transmission packet of another UE.

  Note that as the number of retransmissions increases, the number of retransmission packets decreases, so the signaling of scheduling information transmitted to each UE also decreases. Therefore, when the scheduling information can be identified at a timing earlier than the timing notified in advance (not including the timing notified), the resource control unit 206 of the UE 200 controls to transmit the packet according to the scheduling information. Further, when the scheduling information cannot be identified, the resource control unit 206 performs control so that the packet is transmitted according to the resource notified in advance. Further, the resource control unit 206 controls to stop packet transmission when scheduling information cannot be identified after the previously notified timing (including the notified timing).

Here, it demonstrates concretely using FIG. FIG. 5A shows that the number of retransmission packets decreases as the number of retransmissions increases. FIG. 5B shows the frequency and time resources used by the UE for packet transmission and the presence / absence of scheduling information (grant).

  The base station 100 allocates retransmission resources to the UE 100 and notifies the UE 200 of resource allocation information in advance. Furthermore, the base station 100 notifies the scheduling information at a timing after the retransmission M-th time, and notifies the UE 200 in advance of this timing.

  When the scheduling information is notified from the base station 100 at a timing earlier than the M-th retransmission, the UE 200 transmits a packet according to the scheduling information. In the case of FIG. 5, scheduling information is notified at the first retransmission, and scheduling information is not notified at the retransmission M−1.

  On the other hand, the base station 100 signals scheduling information at the timing after the M-th retransmission. Since the UE 200 knows in advance that the scheduling information is notified, the UE 200 transmits a packet according to the scheduling information notified from the base station 100. In addition, when reception of the scheduling information notified from the base station 100 fails, the UE 200 stops packet transmission.

  In this way, by setting the scheduling information signaling in a period in which the number of retransmission packets decreases, it is possible to suppress an increase in signaling overhead and reduce the number of collisions of transmission packets of the UE.

(Embodiment 2)
The configuration of base station 400 according to Embodiment 2 of the present invention will be described using FIG. FIG. 6 is a block diagram showing a configuration of base station 400 according to Embodiment 2 of the present invention. FIG. 6 differs from FIG. 1 in that the signaling timing determination unit 108 is changed to a signaling timing determination unit 401.

  The signaling timing determination unit 401 associates the signaling timing of the scheduling information with parameters such as transport block size (TBS), QoS delay, presence / absence of frequency hopping of transmission packets, path loss between transmission and reception, etc. Based on the parameters, signaling timing is determined. The determined signaling timing is output to scheduling section 109.

  Note that signaling timing determination section 401 does not output signaling timing (scheduling timing information) to encoding section 110, unlike signaling timing determination section 108 of base station 100 according to Embodiment 1. That is, base station 400 according to the present embodiment does not explicitly notify the scheduling timing information to the UE.

  The configuration of UE 500 according to Embodiment 2 of the present invention will be described using FIG. FIG. 7 is a block diagram showing a configuration of UE 500 according to Embodiment 2 of the present invention. FIG. 7 differs from FIG. 2 in that a signaling timing determination unit 501 is added.

  The signaling timing determination unit 501 has the same function as the signaling timing determination unit 401 of the base station 400, and sets the signaling timing of scheduling information such as TBS of transmission packets, QoS delay, presence / absence of frequency hopping, path loss between transmission and reception, etc. And signaling timing is determined based on these parameters. The determined signaling timing is output to the resource control unit 206.

  The signaling timing determination units 401 and 501 may be any one of the signaling timing of the scheduling information, the TBS of the transmission packet, the QoS delay, the presence / absence of frequency hopping, and the path loss between transmission and reception (only one or only one) Need not be associated).

  Next, various parameters associated with the signaling timing in the above-described signaling timing determination units 401 and 501 will be specifically described. First, the TBS of the transmission packet will be described. A UE that transmits a packet having a large TBS, that is, a large amount of transmission data per packet, sets a short time interval from signaling at the time of initial transmission to signaling of scheduling information at the time of retransmission. On the other hand, for a UE that transmits a packet having a small TBS, that is, a small amount of transmission data per packet, a long time interval is set from the signaling at the initial transmission to the signaling of the scheduling information at the retransmission. Here, the magnitude of the TBS indicates the relative magnitude when both are compared. Similarly, the length of the time interval indicates the relative length when both are compared. The reason for setting in this way is as follows.

  When the TBS is large, the amount of resources used per packet transmission increases, so the number of packets that can be transmitted per transmission time unit (for example, sub-frame) decreases. As a result, the number of scheduling information signaling in the system is reduced. Therefore, the signaling interval of scheduling information can be set short. Also, a packet with a large TBS has a large effect on the system throughput, so the adaptability to propagation path fluctuation is increased. That is, the scheduling information signaling interval is set short, and appropriate resource allocation is performed by following the propagation path fluctuation. Thereby, system throughput can be improved.

  On the other hand, when the TBS is small, the amount of resources used per packet transmission is small, so the number of packets that can be transmitted per transmission time unit is large. As a result, the number of scheduling information signaling in the system increases, and it is necessary to set a longer signaling interval.

  Therefore, when the TBS is large, the scheduling information signaling interval is set short, and when the TBS is small, the scheduling information signaling interval is set long. Thus, by associating the signaling timing of the scheduling information with the TBS in advance, it is possible to reduce the collision occurrence rate between packets without generating an overhead for notifying the signaling timing of the scheduling information.

  Next, the QoS delay of the transmission packet will be described. For a UE that transmits a packet with a small QoS delay, that is, a short time until the packet is discarded due to a transmission delay, a time interval from signaling at the time of initial transmission to signaling of scheduling information at the time of retransmission is set short. On the other hand, for a UE that transmits a packet having a large QoS delay, that is, a long time until the packet is discarded due to a transmission delay, a long time interval is set from the signaling at the initial transmission to the signaling of the scheduling information at the retransmission. To do. Here, the magnitude of the QoS delay indicates a relative magnitude when both are compared. Similarly, the length of the time interval indicates the relative length when both are compared. The reason for setting in this way is as follows.

When the QoS delay is small, the adaptability to propagation path fluctuation is increased. That is, the scheduling information signaling interval is set short, and appropriate resource allocation is performed by following the propagation path fluctuation. As a result, the number of retransmissions is reduced, and the probability that the packet is discarded beyond the request delay is lowered, so that the system throughput can be improved.

  On the other hand, when the QoS delay is large, it takes a long time until the packet is discarded, so that it is highly possible to withstand an increase in the number of retransmissions. That is, the scheduling information signaling interval can be set longer. Therefore, when combined with the case where the QoS delay is small, the signaling overhead of scheduling information can be distributed.

  Therefore, when the QoS delay is large, the scheduling information signaling interval is set to be long, and when the QoS delay is small, the scheduling information signaling interval is set to be short. As described above, by associating the scheduling information signaling timing with the QoS delay in advance, it is possible to reduce the collision occurrence rate between packets without generating an overhead for notifying the scheduling information signaling timing.

  Next, the presence / absence of frequency hopping will be described. For a UE to which frequency hopping is not applied, a time interval from signaling at the time of initial transmission to scheduling information at the time of retransmission is set short. On the other hand, for a UE to which frequency hopping is applied, a time interval from signaling at the time of initial transmission to scheduling information at the time of retransmission is set to be long. The reason for setting in this way is as follows.

  A UE to which frequency hopping is applied has a transmission parameter determined based on the average SINR, and therefore reduces the fitness for instantaneous channel fluctuation. That is, the scheduling information signaling interval can be set longer. Therefore, when combined with the case where frequency hopping is not applied, the signaling overhead of scheduling information can be distributed.

  On the other hand, since the transmission parameter is determined based on the instantaneous SINR, the UE to which frequency hopping is not applied increases the adaptability to the instantaneous propagation path fluctuation. That is, the scheduling information signaling interval is set short, and appropriate resource allocation is performed by following the propagation path fluctuation. Thereby, system throughput can be improved.

  Therefore, when frequency hopping is applied, the scheduling information signaling interval is set long, and when frequency hopping is not applied, the scheduling information signaling interval is set short. In this way, by associating the scheduling information signaling timing with the presence / absence of frequency hopping in advance, it is possible to reduce the collision occurrence rate between packets without generating overhead for notifying the scheduling information signaling timing. it can.

  Next, path loss between transmission and reception will be described. For a UE that has a small path loss, that is, a small amount of propagation path attenuation and a packet that arrives with high reception quality, the time interval from the initial transmission signaling to the retransmission scheduling information signaling is set short. On the other hand, for a UE that has a large path loss, that is, a packet that arrives with low reception quality with a large propagation path attenuation, a long time interval is set from the signaling at the initial transmission to the signaling of the scheduling information at the retransmission. Here, the magnitude of the path loss indicates the relative magnitude when both are compared. Similarly, the length of the time interval indicates the relative length when both are compared. The reason for setting in this way is as follows.

A UE having a small path loss has a low resource consumption for signaling scheduling information, and therefore can transmit scheduling information signaling in the system.
The number increases. Therefore, it is possible to increase the adaptability to propagation path fluctuation, that is, to increase the number of UEs that can set the scheduling information signaling interval to be short, and to improve the system throughput.

  On the other hand, since a UE with a large path loss requires robust transmission, resource consumption for signaling scheduling information increases. As a result, the number of signaling capable UEs of scheduling information per transmission time in the system is reduced, and it is necessary to set a longer signaling interval.

  Therefore, when the path loss is large, the scheduling information signaling interval is set to be long, and when the path loss is small, the scheduling information signaling interval is set to be short. In this manner, by associating the signaling timing of scheduling information with the path loss between transmission and reception in advance, it is possible to reduce the collision occurrence rate between packets without generating overhead for notifying the signaling timing of scheduling information. it can.

  As described above, according to Embodiment 2, the signaling timing of scheduling information is associated with parameters such as TBS of transmission packets, QoS delay, presence / absence of frequency hopping, path loss between transmission and reception, and scheduling is performed based on any parameter. By determining the signaling timing of information, it is possible to reduce the collision occurrence rate between packets without generating overhead for notifying the signaling timing of scheduling information.

(Embodiment 3)
In the first and second embodiments, description has been made assuming uplink packet transmission, but in the third embodiment of the present invention, description will be given assuming downlink packet transmission.

  The base station allocates downlink retransmission resources to each UE in advance, and notifies the UE of resource allocation information in advance. Also, the base station notifies the UE in advance of the timing for notifying scheduling information.

  If the UE receives signaling including scheduling information at a timing other than the timing notified in advance, the UE receives a packet according to the scheduling information. On the other hand, when the scheduling information cannot be received, the packet is received according to the resource allocation information notified in advance. In addition, when the scheduling information cannot be received at the timing notified in advance, the UE stops HARQ combining of the packets.

  As described above, according to the third embodiment, the signaling timing of the scheduling information is notified from the base station to the UE in advance, and when the UE fails to receive the scheduling information at the notified signaling timing, the HARQ combining of the packet is performed. By stopping, it is possible to avoid combining with received packets of other UEs.

  Note that the signaling timing of the scheduling information described in the above embodiments may be a continuous retransmission timing as shown in FIG. Thereby, the reception error of the scheduling information in the signaling timing of scheduling information can be reduced.

In addition, the signaling timing of the scheduling information may be plural times up to the maximum number of retransmissions. Moreover, the signaling timing of scheduling information may be set for each cell.

  In addition, the signaling timing of the scheduling information may be represented by a reference timing and a difference between the reference timing. At this time, the reference timing may be notified by a broadcast channel (for example, BCH (Broadcast Channel)), and the difference from the reference timing may be notified for each UE. Thereby, the bit number of the signaling transmitted for every UE can be reduced.

Further, an offset different for each UE may be added to the signaling timing so that the signaling timing of the scheduling information is different for each UE in the same cell. Thereby, the generation of the signaling timing of the scheduling information can be dispersed in time. Therefore, the downlink control channel (for example, PDCCH (Physical
The probability that scheduling information is transmitted exceeding the capacity that can be accommodated by Dedicated Control Channel)) can be reduced. That is, since scheduling information is not transmitted and the probability of occurrence of unscheduled UEs can be reduced, a decrease in throughput can be suppressed.

  Also, when there is little occurrence of packet fragmentation, as shown in FIG. 9, scheduling information is not transmitted at all other than the signaling timing of scheduling information, that is, non-adaptive HARQ may be applied. Thereby, the collision of the packet between UEs at the time of retransmission can be avoided.

  In addition, regarding the application of non-adaptive HARQ, if the UE cannot acquire the scheduling information at the signaling timing of the scheduling information, the retransmission packet is transmitted via the pre-defined resource at the next non-adaptive HARQ retransmission timing. A transmission method is conceivable. Alternatively, if the UE cannot acquire scheduling information, a method of stopping packet transmission until the next scheduling information is signaled can be considered.

  In addition, a base station may be expressed as NodeB or eNodeB.

  Further, although cases have been described with the above embodiment as examples where the present invention is configured by hardware, the present invention can also be realized by software.

  Each functional block used in the description of each of the above embodiments is typically realized as an LSI which is an integrated circuit. These may be individually made into one chip, or may be made into one chip so as to include a part or all of them. The name used here is LSI, but it may also be called IC, system LSI, super LSI, or ultra LSI depending on the degree of integration.

  Further, the method of circuit integration is not limited to LSI's, and implementation using dedicated circuitry or general purpose processors is also possible. An FPGA (Field Programmable Gate Array) that can be programmed after manufacturing the LSI, or a reconfigurable processor that can reconfigure the connection and setting of circuit cells inside the LSI may be used.

  Further, if integrated circuit technology comes out to replace LSI's as a result of the advancement of semiconductor technology or a derivative other technology, it is naturally also possible to carry out function block integration using this technology. Biotechnology can be applied.

  The disclosure of the specification, drawings and abstract contained in the Japanese application of Japanese Patent Application No. 2008-250616 filed on Sep. 29, 2008 is incorporated herein by reference.

  The radio transmission apparatus and radio transmission method according to the present invention can be applied to, for example, a mobile communication system.

Claims (7)

Resource control means for generating resource control information for controlling resources based on timing for acquiring scheduling information and whether or not the scheduling information is acquired;
Resource selection means for selecting a resource based on the resource control information;
Transmitting means for transmitting data using the selected resource;
Comprising
The resource control unit is a radio transmission apparatus that instructs to stop transmission of the data when the scheduling information is not acquired at the timing.   The radio transmission apparatus according to claim 1, wherein the resource control unit acquires the scheduling information in an N-th retransmission.   The radio transmission apparatus according to claim 1, wherein the resource control unit instructs the transmission stop of the data when the scheduling information is not acquired at the timing associated with a transport block size of data to be transmitted.   The radio transmission apparatus according to claim 1, wherein the resource control unit instructs to stop transmission of the data when the scheduling information is not acquired at the timing associated with a QoS delay of data to be transmitted.   The radio transmission apparatus according to claim 1, wherein the resource control unit instructs the transmission stop of the data when the scheduling information is not acquired at the timing associated with the presence or absence of frequency hopping for the data to be transmitted.   The radio transmission apparatus according to claim 1, wherein the resource control unit instructs the transmission stop of the data when the scheduling information is not acquired at the timing associated with a path loss between transmission and reception. A resource control step for generating resource control information for controlling resources based on the timing for acquiring scheduling information and the presence or absence of acquisition of the scheduling information;
A resource selection step for selecting a resource based on the resource control information;
A transmission step of transmitting data using the selected resource;
Comprising
The said resource control process is a radio | wireless transmission method which instruct | indicates the transmission stop of the said data, when the said scheduling information is not acquired in the said timing.

Images